/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.tsfile.file.metadata.statistics;

import org.apache.iotdb.tsfile.exception.filter.StatisticsClassException;
import org.apache.iotdb.tsfile.file.metadata.enums.TSDataType;
import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.util.Objects;

public class DoubleStatistics extends Statistics<Double> {

    private double minValue;
    private double maxValue;
    private double firstValue;
    private double lastValue;
    private double sumValue;

    static final int DOUBLE_STATISTICS_FIXED_RAM_SIZE = 80;

    @Override
    public TSDataType getType() {
        return TSDataType.DOUBLE;
    }

    /**
     * The output of this method should be identical to the method "serializeStats(OutputStream
     * outputStream)"
     */
    @Override
    public int getStatsSize() {
        return 40;
    }

    /**
     * initialize double statistics.
     *
     * @param min   min value
     * @param max   max value
     * @param first the first value
     * @param last  the last value
     * @param sum   sum value
     */
    public void initializeStats(double min, double max, double first, double last, double sum) {
        this.minValue = min;
        this.maxValue = max;
        this.firstValue = first;
        this.lastValue = last;
        this.sumValue = sum;
    }

    private void updateStats(double minValue, double maxValue, double lastValue, double sumValue) {
        if (minValue < this.minValue) {
            this.minValue = minValue;
        }
        if (maxValue > this.maxValue) {
            this.maxValue = maxValue;
        }
        this.sumValue += sumValue;
        this.lastValue = lastValue;
    }

    private void updateStats(
            double minValue,
            double maxValue,
            double firstValue,
            double lastValue,
            double sumValue,
            long startTime,
            long endTime) {
        if (minValue < this.minValue) {
            this.minValue = minValue;
        }
        if (maxValue > this.maxValue) {
            this.maxValue = maxValue;
        }
        this.sumValue += sumValue;
        // only if endTime greater or equals to the current endTime need we update the last value
        // only if startTime less or equals to the current startTime need we update the first value
        // otherwise, just ignore
        if (startTime <= this.getStartTime()) {
            this.firstValue = firstValue;
        }
        if (endTime >= this.getEndTime()) {
            this.lastValue = lastValue;
        }
    }

    @Override
    void updateStats(double value) {
        if (this.isEmpty) {
            initializeStats(value, value, value, value, value);
            isEmpty = false;
        } else {
            updateStats(value, value, value, value);
        }
    }

    @Override
    void updateStats(double[] values, int batchSize) {
        for (int i = 0; i < batchSize; i++) {
            updateStats(values[i]);
        }
    }

    @Override
    public long calculateRamSize() {
        return DOUBLE_STATISTICS_FIXED_RAM_SIZE;
    }

    @Override
    public Double getMinValue() {
        return minValue;
    }

    @Override
    public Double getMaxValue() {
        return maxValue;
    }

    @Override
    public Double getFirstValue() {
        return firstValue;
    }

    @Override
    public Double getLastValue() {
        return lastValue;
    }

    @Override
    public double getSumDoubleValue() {
        return sumValue;
    }

    @Override
    public long getSumLongValue() {
        throw new StatisticsClassException(
                String.format(STATS_UNSUPPORTED_MSG, TSDataType.DOUBLE, "long sum"));
    }

    @Override
    protected void mergeStatisticsValue(Statistics<Double> stats) {
        DoubleStatistics doubleStats = (DoubleStatistics) stats;
        if (this.isEmpty) {
            initializeStats(
                    doubleStats.getMinValue(),
                    doubleStats.getMaxValue(),
                    doubleStats.getFirstValue(),
                    doubleStats.getLastValue(),
                    doubleStats.sumValue);
            isEmpty = false;
        } else {
            updateStats(
                    doubleStats.getMinValue(),
                    doubleStats.getMaxValue(),
                    doubleStats.getFirstValue(),
                    doubleStats.getLastValue(),
                    doubleStats.sumValue,
                    stats.getStartTime(),
                    stats.getEndTime());
        }
    }

    @Override
    public int serializeStats(OutputStream outputStream) throws IOException {
        int byteLen = 0;
        byteLen += ReadWriteIOUtils.write(minValue, outputStream);
        byteLen += ReadWriteIOUtils.write(maxValue, outputStream);
        byteLen += ReadWriteIOUtils.write(firstValue, outputStream);
        byteLen += ReadWriteIOUtils.write(lastValue, outputStream);
        byteLen += ReadWriteIOUtils.write(sumValue, outputStream);
        return byteLen;
    }

    @Override
    public void deserialize(InputStream inputStream) throws IOException {
        this.minValue = ReadWriteIOUtils.readDouble(inputStream);
        this.maxValue = ReadWriteIOUtils.readDouble(inputStream);
        this.firstValue = ReadWriteIOUtils.readDouble(inputStream);
        this.lastValue = ReadWriteIOUtils.readDouble(inputStream);
        this.sumValue = ReadWriteIOUtils.readDouble(inputStream);
    }

    @Override
    public void deserialize(ByteBuffer byteBuffer) {
        this.minValue = ReadWriteIOUtils.readDouble(byteBuffer);
        this.maxValue = ReadWriteIOUtils.readDouble(byteBuffer);
        this.firstValue = ReadWriteIOUtils.readDouble(byteBuffer);
        this.lastValue = ReadWriteIOUtils.readDouble(byteBuffer);
        this.sumValue = ReadWriteIOUtils.readDouble(byteBuffer);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        if (!super.equals(o)) return false;
        double e = 0.00001;
        DoubleStatistics that = (DoubleStatistics) o;
        return Math.abs(that.minValue - minValue) < e
                && Math.abs(that.maxValue - maxValue) < e
                && Math.abs(that.firstValue - firstValue) < e
                && Math.abs(that.lastValue - lastValue) < e
                && Math.abs(that.sumValue - sumValue) < e;
    }

    @Override
    public int hashCode() {
        return Objects.hash(super.hashCode(), minValue, maxValue, firstValue, lastValue, sumValue);
    }

    @Override
    public String toString() {
        return super.toString()
                + " [minValue:"
                + minValue
                + ",maxValue:"
                + maxValue
                + ",firstValue:"
                + firstValue
                + ",lastValue:"
                + lastValue
                + ",sumValue:"
                + sumValue
                + "]";
    }
}
